1. Field of Invention
This invention relates to an active matrix display device.
2. Description of Related Art
The deterioration of liquid crystal is prevented by the common AC driving that gives AC potential to a common electrode and a supplemental capacitance in the active matrix display device where an image signal is applied to a pixel electrode through a switching element such as a thin film transistor (TFT). Also, low energy consumption is achieved by lowering both electric current and voltage of a drain driver through the minimization of the voltage difference between the positive and negative polarities of video signal inputted to the drain driver. The voltage polarity of the common electrode and all the supplemental capacitance lines is inverted at each horizontal period in a line inversion driving system where polarity of the video signal given to the drain line is inverted at each horizontal period during the common AC driving.
The Japanese patent publication 2003-150127 discloses the common DC dot inversion driving system, in which the video voltages with opposite polarities are applied to the pixels in such way that any pair of the adjacent pixels in horizontal and vertical direction have opposite polarity from each other by supplying the video voltage with opposite polarities to the pixel electrodes next to each other in gate line direction with the voltage Vcom of the common electrode potential as the DC potential.
However, line-flicker easily appears in the line inversion driving system, deteriorating the display quality. Although the common DC dot inversion driving system can achieve the high quality display since it does not cause line-flicker, its energy consumption is large because of the wider dynamic range of the video signals V, V* (signal V* signifies the signal with the opposite polarity from that of signal V) as shown in FIG. 12.